Turbo-jet engines use oil during operation. This fluid is used for lubrication, but also for heat exchanges. Heat exchanges means both cooling certain components and heating numerous zones subject to icing. Furthermore, the oil may be pressurized in order to actuate hydraulic cylinders.
This fluid plays a crucial role, and therefore must be properly conserved and the quantity of oil available in the turbo-jet engine must be precisely measured. To satisfy this latter requirement, oil tanks commonly have a window for showing the level of liquid stored. The window is a piece of transparent glass enabling the inside of the tank to be checked by simple visual inspection.
Patent application US 2015/0260563 A1 proposes a tank for an aeroplane including direct oil-level vision device and an independent electronic sensor. This independent sensor can work automatically by measuring the capacitance of the oil contained in the tank. However, although this independent sensor improves the correlation of the measurement of the oil level in the tank with the direct vision device, the sensor occupies a certain volume inside the tank. Moreover, installing the sensor inside the storage space is complex.
Furthermore, specific attachment means are provided to keep the sensor independent inside the tank. These attachment means may include pins cooperating with through-holes, or welds. Since sealing must be guaranteed under extreme conditions, additional measures are then required. Furthermore, complex quality and sealing checks are also required.